Just had a new battery installed 2 weeks ago at Firestone. Firestone said that I also needed a new alternator. Decided to bring vehicle to dealership. They said nothing wrong with alternator, but I needed to replace the tensioner and Serpentine Belt, which I did. Vehicle lost power last night with lights going off, radio going off and on, lights on dash board going on and off. Turned off a/c and drove car back home. Vehicle electrical system charging at 13,98 V 81 amps. Replaced all hoses, new battery, changed oil and filter. Any suggestions as to what is wrong. Thanks. Barbara
How many new batteries? one or two? 13.98 volts, 81 amps is great! How did you determine those numbers? Sometimes alternators can fool you when they fail…The failure can be intermittent. Have an auto-electric shop check the alternator again…Make sure there is no “A/C ripple” in its output.
Oh, while an alternator might be RATED to produce 81 amps, it’s almost impossible to get one to actually produce 81 amps for more than a few seconds…
Didn’t Stephen King do a book on this one? OK, just kidding.
For starters, I’d go back to the dealer that sold you the new timing belt and tensioner and ask them to correctly install and retension them. That should be covered under the shop warranty as it sounds like something may have slipped after they closed it up. Then ask them to properly diagnose the electrical problem without replacing anything this time. When they present you with a new estimate, take it to an electrical shop as suggested earlier, or at least an independent that can perform electrical/charging system tests and see if they agree on the diagnosis. If not, I’d go with the independent.
Along with a charging system test they check out all the usual electrical suspects like loose clamps, connectors, belts etc. It could be a short in the electrical or yes, diodes or a bad alternator or even a bad regulator which would be unusual but not out of the question given the age of the car. They’ll determine whether charging is within normal limits and they can check the specs to ensure that Firestone installed the right battery. You can find a great electrical shop / mechanic on the home page here, right hand side by zip code.
I’m taking your advice and going with an independen. I explained the problem to the independent mechanic and he said that he has the equipment to check it out to determine what is going on. I’m also taking your notes with me. My car has 70,000 miles on it and it is a very confortable vehicle. I have been looking at new vehicles but can’t find anything that rides like my vehicle. Thanks again.